Field
This invention relates generally to a pneumatically-actuated fastening device and, more particularly, to a fastening device for connecting a work piece to a structure, where the device uses a sequence of pneumatic events to latch or unlatch the work piece, the device is fully retractable in the unlatched position and thus suitable for use around the periphery of a highly curved work piece, and deployment of the device is temporally staged via a pressure chamber with a bleed orifice located in a pneumatic piston.
Discussion
Various industries, including aviation, general construction, electronics, and general manufacturing, use fasteners for a number of different purposes. For example, the aviation industry may find it desirable to quickly, reliably, and robustly attach Outer Mold Line (“OML”) frequently-accessed panels and doors to an aircraft's structural frame. The fastenings methods used to attach these OML panels and doors should be secure and capable of avoiding undesired and/or accidental detachment (e.g., during flight). In certain aviation applications, it may also be desirable to reduce aerodynamic drag by using fasteners that hold these OML panels and doors from underneath, thereby avoiding protrusions or penetrations through the OML of the panel or door. In this situation, a fastener could be associated with the structural beam and actuated from beneath the panel to grab or grasp the panel, when actuated.
Panel fasteners may be designed for an initial actuation or installation by a user to a particular clamp-up force. Due to the desire for reliable service, panel fasteners in certain use environments, such as aviation, might then be designed to hold the initial clamp-up force without further application of energizing force until such time as a de-energizing force is positively applied by the user to facilitate selective panel removal.
Panel fasteners have been developed which hold the panel from underneath, as described above. However, in the unlatched position, these fasteners protrude above the structure onto which the panel is to be fastened. Thus, such fasteners are not suitable for highly curved panels, because the multiple protruding fasteners would interfere with and prevent the panel from being placed into position on the structure. A panel fastener is needed which holds the panel from underneath, and which is fully retractable into the supporting structure when in the unlatched position.